1. Field of the Invention
The present invention relates generally to an apparatus for fabricating a semiconductor device, and more particularly to an apparatus for fabricating a semiconductor device further comprising an additional plasma electrode within a reactor so that the inside of the reactor can be cleaned effectively by plasma.
2. Description of the Related Art
In general, many semiconductor wafer fabrication processes carried out in RF (Radio Frequency) plasma reactors leave contaminant deposits on the reactor chamber walls, which accumulate and become the source of particles harmful to the yield of a semiconductor device. Accordingly, the reactor is required to be cleaned frequently to prevent any undesired particles from being produced within the reactor during fabricating of a semiconductor device within the reactor. In general, in a semiconductor device fabricating process using plasma, plasma which is used in the fabricating process is used itself for cleaning the inside of the reactor. However, when the reactor has a complex structure, the reactor may not be cleaned everywhere due to the geometric configuration of the reactor. Therefore, an additional wet cleaning is required frequently, which is subject to generation of undesired particles during a process for fabricating a semiconductor device.
FIG. 1 is a schematic view for illustrating an apparatus for fabricating a semiconductor device according to the prior art.
In particular, the reactor which provides a reaction region separated from outside comprises a chamber 60 and a quartz dome 30 covering the upper portion of the chamber 60. The quartz dome 30 is covered with a bell jar 10, the inside of which is configured like a dome, and a plasma electrode 20, covering the inner wall of the bell jar 10, is disposed between the quartz dome 30 and the bell jar 10. The plasma electrode 20 configured like a dome is connected to an RF power supply 50 via an RF cable 40.
A substrate transport port 70 for loading a semiconductor substrate into the chamber 60 is arranged in the side wall of the chamber 60, and a pedestal 80 for supporting the loaded semiconductor substrate is placed inside the chamber 60. Here, the substrate transport port 70 is opened and closed by a slot valve (not shown). The pedestal 80 can move up and down using supporting means 90. A gas inlet and a gas outlet for introducing and exhausting gas into/from the reactor are not shown for the sake of brevity.
A method for forming a thin film on a semiconductor substrate by using such an apparatus as shown in FIG. 1 is as follows:
First, a semiconductor substrate is loaded into the chamber 60 through the substrate transport port 70 and settled onto the pedestal 80. Then, the pedestal 80 is positioned at the optimal height for the process to be performed by using the supporting means 90. In this state, the inside of the reactor is evacuated into a high vacuum state by a vacuum pump (not shown).
Then, gas is introduced and RF power is applied to the plasma electrode 20 to generate plasma. In this case, plasma is not generated in the region lower than the pedestal 80 or in the substrate transport port 70, but generated only between the pedestal 80 and the plasma electrode 20. When the generated plasma is stabilized, source gas is introduced to form a film on the semiconductor substrate.
When the film forming process described above is over, the semiconductor substrate is unloaded from the reactor, and then plasma is generated again as the same way as above to perform a dry cleaning to the inside of the reactor by using the generated plasma. But plasma is generated only between the pedestal 80 and the plasma electrode 20 as described above, the dry cleaning by the generated plasma is not performed in the region lower than the pedestal 80 and in the substrate transport port 70.
Therefore, an additional wet cleaning is required frequently in the region lower than the pedestal 80 and in the substrate transport port 70, thereby causing a problem that undesired particles are generated during a process for fabricating a semiconductor device.
Therefore, it is an object of the present invention to provide an apparatus for fabricating a semiconductor device which comprises an additional plasma electrode for cleaning the inside of a reactor so that the reactor can be cleaned everywhere without performing an additional wet cleaning.
According to an embodiment of the present invention to achieve the foregoing object, it is provided an apparatus for fabricating a semiconductor device comprising: a reactor for providing a reaction region separated from outside; a pedestal arranged within the reactor to support a semiconductor substrate; a substrate transport port for loading the semiconductor substrate into the reactor; and upper and lower plasma electrodes for generating plasma within the reaction region, the upper and lower plasma electrodes being disposed in the upper and lower portions of the reaction region in respect to the pedestal, respectively.
The apparatus for fabricating a semiconductor device of the present invention may further comprise a slot valve plasma electrode within the substrate transport port, the slot valve plasma electrode being connected to the lower plasma electrode via an RF wire.
The upper and lower plasma electrodes may be connected to the same RF power supply, wherein an additional RF relay may be preferably provided for alternatively supplying RF power from the RF power supply to the upper or lower plasma electrode. Here, the RF relay electrically connects the RF power supply and the upper plasma electrode for supplying RF power only to the upper plasma electrode when an external input signal is not applied to the RF relay, and electrically connects the RF power supply and the lower plasma electrode while electrically disconnecting the upper plasma electrode from the RF power supply for supplying RF power to the lower plasma electrode when an external input signal of 24 V is applied to the RF relay.